> I can't speak for the other applications, but have you used Hipchat? It's really poor in comparison to Slack.
You're splitting hairs. They are both chat apps for crying out loud.
Slack grew as fast as it did because it got pimped to us by VCs and thought leaders and then wannabe thought leaders and down all the way to the bottom rung of the societal ladder. Great strategy by Slack but there is nothing special about it (the product).
I wouldn't be so sure. Slack was just a better product overall, offering a clear interafce and much better integrations than Hipchat. Hipchat being slow did not impact them as much as having a mediocre product to begin with.
About Yammer, I wouldn't really put it in the same bucket as Slack, as it really tries to be a Facebook for your company, not a group chat.
There is an existing baseline before Slack was released that you can take as a rough baseline.
It's true though - Hipchat was caught napping. Atlassian backburner'd it at exactly the wrong time, and by the time they starting fixing things, it was too late.
This being said, Atlassian isn't really a 'startup' anymore. Hipchat is a side-product of a suite of gorilla products.
This Google trends line is interesting: https://www.google.com/trends/explore#q=slack%2C%20hipchat%2...